Patent Literature 1 discloses a rotor of a motor, which is a rotor for an inner rotary type motor, including an outer core facing an inner periphery of a stator and forming a magnetic path of the stator necessary for rotation, an inner core fixedly attached to a shaft to transmit rotational force to the shaft, and an elastic material such as a rubber material with which a gap between the outer core and the inner core is filled. The motor rotor described in Patent Literature 1 has a plurality of projections facing each other on an inner periphery side of the outer core and on an inner periphery side of the inner core, and at least one of the projection of the outer core and the projection of the inner core is covered with the elastic material such as a rubber material.